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Abstract: The toxicokinetics of mercury (Hg) in key species of Arctic ecosystem are poorly understood. We sampled five brain regions (frontal lobe, temporal lobe, cerebellum, brain stem and spinal cord) from beluga whales (Delphinapterus leucas) harvested in 2006, 2008, and 2010 from the eastern Beaufort Sea, Canada, and measured total Hg (HgT) and total selenium (SeT) by inductively coupled plasma mass spectrometry (ICP-MS), mercury analyzer or cold vapor atomic absorption spectrometry, and the chemical forms using a high performance liquid chromatography ICP-MS. At least 14% of the beluga whales had HgT concentrations higher than the levels of observable adverse effect (6.0mgkg−1 wet weight (ww)) in primates. The concentrations of HgT differed between brain regions; median concentrations (mgkg−1 ww) were 2.34 (0.06 to 22.6, 81) (range, n) in temporal lobe, 1.84 (0.12 to 21.9, 77) in frontal lobe, 1.84 (0.05 to 16.9, 83) in cerebellum, 1.25 (0.02 to 11.1, 77) in spinal cord and 1.32 (0.13 to 15.2, 39) in brain stem. Total Hg concentrations in the cerebellum increased with age (p<0.05). Between 35 and 45% of HgT was water-soluble, of which, 32 to 41% was methyl mercury (MeHg) and 59 to 68% was labile inorganic Hg. The concentration of MeHg (range: 0.03 to 1.05mgkg−1 ww) was positively associated with HgT concentration, and the percent MeHg (4 to 109%) decreased exponentially with increasing HgT concentration in the spinal cord, cerebellum, frontal lobe and temporal lobe. There was a positive association between SeT and HgT in all brain regions (p<0.05) suggesting that Se may play a role in the detoxification of Hg in the brain. The concentration of HgT in the cerebellum was significantly associated with HgT in other organs. Therefore, HgT concentrations in organs that are frequently sampled in bio-monitoring studies could be used to estimate HgT concentrations in the cerebellum, which is the target organ of MeHg toxicity. [Copyright &y& Elsevier]

Increasing evidence shows that persistent organic pollutants such as perfluorinated compounds (PFCs) are found in the Arctic ecosystem and their prevalence is causing human health concerns. The objective of this study was to estimate dietary exposure to PFCs among Inuit in northern Canada. Perfluorooctane sulfonate (PFOS), perfluorinated carboxylates (PFCA C7–C11) and fluorotelomer unsaturated carboxylic acids (6:2, 8:2 and 10:2 FTUCA) were measured in 68 traditional foods collected in Nunavut between 1997 and 1999. Total PFC concentrations were highest in caribou liver (mean±standard deviation; 6.2±5.5ngg−1), ringed seal liver (minimum, maximum; 7.7, 10.2ngg−1), polar bear meat (7.0ngg−1), and beluga meat (minimum, maximum; 7.0, 5.8ngg−1). Inuit food intake data from 24-h recalls conducted in Nunavut between 1997 and 1999 were used for the calculation of PFC exposure. Mean daily dietary exposure was calculated to range from 210 to 610ng person−1 (0.6–8.5ngkg body weight−1) for 754 individuals. Dietary exposure to PFCs was statistically significantly higher in men in the 41–60year age group (p <0.05) than younger men (<40years old) and women from the same age group. Traditional foods contributed a higher percentage to PFC exposure than market foods in all age and gender groups. Caribou meat contributed 43–75% of daily PFC dietary exposure. Health risks associated with these estimated exposure levels are minimal based on current toxicological information available from animal feeding studies. However, it is important to monitor the concentrations of PFCs in key food items given that PFCA levels have been found to be increasing in the Canadian Arctic. [Copyright &y& Elsevier]